P8serial

Pulse 8 Serial protocol

The P8Serial protocol is the semi-proprietary protocol that the Pulse-Eight CEC-USB adapter uses to communicate with libcec. The information on this page has been collected by analysing the actual packets, as sent over the serial line, and reading the libcec code.

Framing

Each packet starts with 0xFF and end with 0xFE. Every 0xFF, 0xFE and 0xFD is escaped with 0xFD, followed by byte - 3 . The start byte is followed by the opcode, and then parameters (if any). The opcodes can be found in src/lib/adapter/Pulse-Eight/USBCECAdapterMessage.h and in the table below.

Each frame sent by the host is explicitly acknowledged, either by an ACK frame or by sending back a reply using the same opcode as in the command. The adapter also sends unsolicited frames; the host does not need to acknowledge them.

Commands

Code	Name	Parametrs	Notes
01	PING	-	Used to ping every 5 seconds
02	TIMEOUT_ERROR
03	HIGH_ERROR
04	LOW_ERROR
05	FRAME_START	src:dst	Receive CEC src:dst
06	FRAME_DATA	b	Receive next CEC byte
07	RECEIVE_FAILED
08	COMMAND_ACCEPTED	-	Normal ack for most commands
09	COMMAND_REJECTED
0A	SET_ACK_MASK
0B	TX	B	Send next CEC byte
0C	TX_EOM	B	Send last CEC byte
0D	TX_IDLETIME
0E	TX_ACK_POLARITY	pol src:dst	Send CEC src:dst, assure ack
0F	TX_LINE_TIMEOUT
10	TX_SUCCEEDED
11	TX_FAILED_LINE
12	TX_FAILED_ACK
13	TX_FAILED_TIMEOUT_DATA
14	TX_FAILED_TIMEOUT_LINE
15	FIRMWARE_VERSION
16	START_BOOTLOADER
17	GET_BUILDDATE
18	SET_CONTROLLED
19	GET_AUTO_ENABLED
1A	SET_AUTO_ENABLED
1B	GET_DEFAULT_LOGICAL_ADDRESS
1C	SET_DEFAULT_LOGICAL_ADDRESS
1D	GET_LOGICAL_ADDRESS_MASK
1E	SET_LOGICAL_ADDRESS_MASK
1F	GET_PHYSICAL_ADDRESS
20	SET_PHYSICAL_ADDRESS
21	GET_DEVICE_TYPE
22	SET_DEVICE_TYPE
23	GET_HDMI_VERSION
24	SET_HDMI_VERSION
25	GET_OSD_NAME
26	SET_OSD_NAME
27	WRITE_EEPROM
28	GET_ADAPTER_TYPE

Command flags

Code	Name	Notes
40	FRAME_ACK
80	FRAME_EOM